In each of the following situations, indicate whether the potential bias is a selection bias, a nonparticipation bias, or a response bias.

a. A survey question asked of unmarried men was, "What is the most important feature you consider when deciding whether to date somebody?" The results were found to depend on whether the interviewer was male or female.

b. In a study of women's opinions about community issues, investigators randomly selected a sample of households and interviewed a woman from each selected household. When no woman was present in a selected household, a next-door neighbor was interviewed instead. The survey was done during daytime hours, so working women might have been disproportionately missed.

c. A telephone survey of 500 residences was conducted. People refused to talk to the interviewer in 200 of the residences.